ICE Toolkit

The ICE tool requires the use of Javascript to enable it's many useful features. If you cannot enable Javascript though, don't worry. You can produce the same results on your own with a little help. The Download Model Data page allows users to download Microsoft Excel spreadsheets of the model statistics for each available model. All variables needed to conduct model calculations can be located there.

You will need to identify your surrogate species or predicted species/family/genus and use the tables to find matching data to run your calculations. The predicted taxa toxicity can be calculated as:

y = 10^[ a + b*Log10(x)]

Where x is the toxicity value of the surrogate species, and a and b are the intercept and slope, respectively. The lower and upper confidence bounds are calculated as:

Lower bound = 10^ {Log10(y) - t%CI*sqrt [MSE*1/(df+2)+(x*-x)2/Sxx ] }

Upper bound = 10^ {Log10(y) + t%CI*sqrt [MSE*1/(df+2)+(x*-x)2/Sxx ] }

Where y is the estimated toxicity value of predicted taxa, t%CI is the value of t at the desired confidence level (90%, 95%, 99%), MSE is the mean square error, and Sxx is the sum of squared deviations of the surrogate (Dowdy and Wearden 1991).